CN1385666A - Computer time-division control technology for oxygen consumption in electric arc furnace - Google Patents

Abstract

The invention relates to a time-segmented control technology for oxygen use in an electric arc furnace, which divides various oxygen use modes into several modules. The modules include a total oxygen module, an oxygen combustion and fluxing module, a furnace door oxygen blowing module, and an eccentric furnace bottom of an electric furnace—— EBT oxygen blowing module, secondary combustion module, cluster oxygen lance module and carbon injection module, according to the smelting characteristics of the electric arc furnace and the function of the specific oxygen supply module, different time points are determined, and the oxygen flow and other medium flow requirements in each time period Calculate according to the oxygen supply purpose of the specific module, and the calculation basis is determined by empirical data and formulas; in terms of control method, PID control in the negative feedback control method is adopted. The invention combines oxygen modular control technology, reduces oxygen consumption by 10-20%, increases metal yield by 1-2%, reduces electrode consumption by 0.3-0.5kg/t, and reduces smelting power consumption by 35-50kWh/t.

Description

Computer time-division control technology for oxygen consumption in electric arc furnace

Technical field:

The invention belongs to field of steel-making, be specially adapted to the oxygen consuming amount control of electric-arc furnace steelmaking.

Background technology:

At present, adopt the electric arc furnaces of blowing oxygen technology, purpose all is to flux for oxygen blast, smelts the winding-up amount of the oxygen in stage for difference and does not generally do strict chemical equilibrium and material balance calculating.Practical effect is that flow of oxygen is excessive, and CO content is higher in the furnace gas, and electrode and conductive cross arm are oxidized serious, and recovery rate of iron is low.

Summary of the invention:

The technical problem to be solved in the present invention is: pass through computer control system, raw material condition according to every stove, utilize material balance and thermal equilibrium to determine rational oxygen-supplying amount, then in conjunction with each the smelting stage in the stove, the oxygen-supplying amount that decomposes different oxygen supply modes, regulate oxygen flow and other fuel flow rate of each module by control system, these adjustings affact on the respective valve group via fieldbus and PLC, the actual flow of control oxygen and other fuel, solve the balanced winding-up problem of electric arc furnaces oxygen, improve recovery rate of iron, reduce consumption of electrode, reduce melting electric consumption.

Control procedure of the present invention is by the electric arc furnaces computer control system, raw material condition according to every stove, utilize material balance and thermal equilibrium to determine rational oxygen-supplying amount, then in conjunction with each the smelting stage in the stove, the oxygen-supplying amount that decomposes different oxygen supply modes, regulate oxygen flow and other fuel flow rate of each module by control system, these adjustings affact on the respective valve group via fieldbus and PLC, the actual flow of control oxygen and other fuel.In the production run, control system is constantly revised each controlled variable according to the data that various surveying instruments feed back, and finally reaches optimum control.

Computer time-division control technology for oxygen consumption in electric arc furnace, various way of oxygen use are divided into module one by one, module comprises total oxygen module, oxygen combustion fluxing module, fire door oxygen blast module, the eccentric furnace bottom of electric furnace--EBT oxygen blast module, secondary combustion module, coherent oxygen lance module and spray carbon module is characterized in that; Smelting characteristic according to electric arc furnaces has been determined different period points with the function of concrete oxygen supply module, and the oxygen flow in each period and other rate-of flow need to calculate according to the oxygen supply purpose of concrete module, and basis is determined by empirical data and formula; On the control method, adopt the PID control in the negative feedback control method.Oxygen combustion fluxing module oxygen supply at times control curve, fuel oil are controlled curve at times, and figure four for fire door oxygen blast module oxygen supply at times control curve, the eccentric furnace bottom of electric furnace--EBT oxygen blast module oxygen supply at times control curve is seen Fig. 1 respectively--

Aforesaid computer time-division control technology for oxygen consumption in electric arc furnace is characterized in that oxygen combustion fluxing module controls the delivery rate of the system's intermediate fuel oil of fluxing at times and be:

F _oil＝60·W _S·V _oil/τ

The delivery rate of oxygen is in the system of fluxing: $F_O=\frac{60{\mathrm{<figure-callout\; id="1"\; label="k"\; filenames="A0211650600063.png"\; state="\{\{state\}\}">k</figure-callout>}}_1\&CenterDot;W_S\&CenterDot;q\&CenterDot;V_{\mathrm{oil}}\&CenterDot;V_O}{(1+\frac{0.21k_2\mathrm{\&alpha;}}{100{-k}_2\mathrm{\&alpha;}})\mathrm{\&tau;}}$

The delivery rate of atomizing air is in the system of fluxing: $F_A=\frac{60{\mathrm{<figure-callout\; id="1"\; label="k"\; filenames="A0211650600063.png"\; state="\{\{state\}\}">k</figure-callout>}}_1\&CenterDot;W_S\&CenterDot;q\&CenterDot;V_{\mathrm{oil}}\&CenterDot;V_O}{(\frac{100}{k_2\mathrm{\&alpha;}}-0.79)\mathrm{\&tau;}}$

The present invention can make the winding-up of electric arc furnaces oxygen reach efficient, reasonable and economical, in conjunction with using oxygen modularization control technology, flow of oxygen reduces by 10～20%, and can improve recovery rate of iron 1～2%, reduce consumption of electrode 0.3～0.5kg/t, reduce melting electric consumption 35～50kWh/t.

Description of drawings: Fig. 1 is the curve of control at times of oxygen combustion fluxing module oxygen.Fig. 2 is the curve of control at times of oxygen combustion fluxing module fuel oil.Fig. 3 controls curve at times for fire door oxygen blast module.Fig. 4 controls curve at times for EBT oxygen blast module.

Embodiment:

Period point is for different oxygen supply modules because the purpose difference of its oxygen supply in electric arc furnaces, therefore concrete divide the time hop count also should be inequality, should be target with the utilization factor that improves oxygen.

According to the characteristics of electric arc furnace smelting, the adding of furnace charge is normally carried out in batches, and mostly furnace charge is solid matter.Furnace charge adds fashionable, and each oxygen system is quit work substantially, but for anti-block rifle or burner is blocked should keep certain oxygen flow.After reinforced finishing, a large amount of steel scraps or other iron and steel stock are deposited near oxygen rifle or the burner outlet, if big immediately flow is blown into oxygen, owing to there are not enough combustion spaces, most of oxygen will be wasted, can't reach oxygen blown purpose at all, electric arc furnaces ton steel oxygen consumption be increased, and can increase the oxidation of electrode and conductive cross arm.Therefore, near the time point of reinforced beginning and end, should be one of waypoint of oxygen supply module.After iron and steel stock melts certain space near oxygen rifle or the burner, just can use the adjustment oxygen flow to carry out the winding-up of peak power.After the last batch of iron and steel stock is molten clear, should oxygen decarburization, should adjust the oxygen flow of corresponding oxygen supply module this moment, so that effectively remove the carbon in the molten steel.After decarburization finished, oxygen system should only keep less oxygen flow, made oxygen rifle or burner be unlikely to stop up.Specific to each oxygen supply module, the division of period has scarcely together.

In each oxygen supply module, the oxygen flow in each period and other rate-of flow need to calculate and empirical data or formula are determined according to the oxygen supply purpose of concrete module.Generally speaking, the operate as normal flow of equipment is to calculate according to theory or experimental formula in the module, and the flow under the various non-normal working needs to determine according to empirical data in the past.

Electrode after every batch of material adds is worn the well stage, fill steel scrap in the stove, hole is less, can not provide fuel combustion required space fully, therefore should carry out the igniting of oil-oxygen smelt-supporting burner with less oxygen flow and fuel flow, and the cutting steel scrap has formed bigger space.Along with the formation of enough combustion spaces, the top condition of fluxing possesses, should use normal oxygen flow and fuel flow.When scrap melting finishes 50%, the decrease in efficiency of fluxing, should reduce the energy of burner input this moment.When not having steel scrap on the slag line, should stop the supply of fuel oil, keep lower oxygen anti-blocking.And in the heat of oxidation, the reaction between carbon and oxygen aggravation produces a large amount of CO gases in the stove, does not have at electric arc furnaces under the situation of secondary combustion oxygen rifle, and the oxygen flow that can suitably increase oily oxygen rifle carries out secondary combustion.

The delivery rate that oxygen combustion fluxing module is controlled the system's intermediate fuel oil of fluxing at times is:

F _oil＝60·W _S·V _oil/τ

The delivery rate of oxygen is in the system of fluxing: $F_O=\frac{60{\mathrm{<figure-callout\; id="1"\; label="k"\; filenames="A0211650600063.png"\; state="\{\{state\}\}">k</figure-callout>}}_1\&CenterDot;W_S\&CenterDot;q\&CenterDot;V_{\mathrm{oil}}\&CenterDot;V_O}{(1+\frac{0.2k_2\mathrm{\&alpha;}}{100-k_2\mathrm{\&alpha;}})\mathrm{\&tau;}}$

The delivery rate of atomizing air is in the system of fluxing: $F_A=\frac{60{\mathrm{<figure-callout\; id="1"\; label="k"\; filenames="A0211650600063.png"\; state="\{\{state\}\}">k</figure-callout>}}_1\&CenterDot;W_S\&CenterDot;q\&CenterDot;V_{\mathrm{oil}}\&CenterDot;V_O}{(\frac{100}{k_2\mathrm{\&alpha;}}-0.79)\mathrm{\&tau;}}$

Fire door oxygen blast module is controlled at times

The fire door blowing oxygen quantity is based on that chemical equilibrium and material balance calculate, mainly by decisions such as the carbon content in the raw material and other element amount of oxidation.Calculate according to material balance,, utilize the electric arc furnaces static model can calculate a ton steel oxygen consumption easily, thereby determine the oxygen delivery rate in conjunction with the empirical value of modern electric arc furnaces.

Because during modern ultra high electric arc furnace is smelted, in order to obtain stable electric arc and to shorten the heat, often add carbon dust to carry out long arc foaming slag operation, certain oxygen of so just must jetting in electric furnace makes the carbon dust burning.Suppose that generating product is CO gas.Can obtain the oxygen demand of this operation thus: $O=\frac{16}{12}\&CenterDot;\mathrm{MC}\&CenterDot;(\%\mathrm{CP})$

The oxygen flow control of fire door oxygen lance also can be carried out segmentation control according to the sampling moment and steel sample analysis result in the smelting process, and accompanying drawing 7 has shown the program circuit of this control.At first, according to the charging situation, utilize material balance to calculate the oxygen flow of initially jetting.Smelting proceeds to certain hour, and sample analysis recomputates the residue oxygen flow of the duration of heat according to analysis result.Carry out this process repeatedly, up to satisfying the smelting endpoint requirement.

EBT oxygen blast module is controlled at times

In EBT oxygen blast module, oxygen mainly is to be used for cutting melting waste steel, and evenly bath temperature and composition if necessary also can carry out decarburization.In control, before and after charging the situation identical with the oil-oxygen smelt-supporting module, when heat of oxidation decarburization, EBT oxygen should be jetted with the operate as normal flow.The smoke evacuation ability design of exhaust smoke hole on exhaust gas volumn that the oxygen that the main basis of EBT oxygen rifle is blown into produces and the bell.

The secondary combustion module

The Theoretical Calculation of secondary combustion module controls oxygen-supplying amount mainly is the decarburized amount, spray carbon amount according to the molten bath etc.According to mass balance as can be known, the ton steel oxygen expenditure of secondary combustion oxygen rifle is: $V_{O_2\&CenterDot;\mathrm{pc}}=0.933W_C\&CenterDot;\mathrm{\&Delta;PCR}$

After the ton steel oxygen consumption of known secondary combustion oxygen rifle, can calculate oxygen flow by following formula: $F_{O_2\&CenterDot;\mathrm{PC}}=V_{O_2\&CenterDot;\mathrm{PC}}\&CenterDot;W_S/{\mathrm{\&tau;}}_{\mathrm{PC}}$

Cluster fluidic oxygen gun mainly is to be used for substituting existing oxygen rifle to use, and therefore, determining of its dividing time-steps and day part flow is mainly definite according to the oxygen blast module that is substituted, and no longer carries out concrete discussion.

According to above principle, can design electric arc furnaces oxygen modularization control system in conjunction with Computer Control Technology.In control system, function such as comprise that the control interface, real-time curve of each module shows, history curve inquiry, various report display and printing, historical data are browsed and inquired about.This control system can store, extract various a large amount of production datas, can carry out each control of using the oxygen module etc.

Claims (2)

1. A time-segmented oxygen computer control technology for electric arc furnaces, which divides various oxygen consumption methods into modules. The modules include the total oxygen module, the oxygen combustion boosting module, the furnace door oxygen blowing module, and the eccentric furnace bottom of the electric furnace--EBT The oxygen blowing module, the secondary combustion module, the cluster oxygen lance module and the carbon injection module are characterized in that different time points are determined according to the smelting characteristics of the electric arc furnace and the functions of the specific oxygen supply module, and the oxygen flow rate and other The medium flow needs to be calculated according to the oxygen supply purpose of the specific module, and the calculation basis is determined by empirical data and formulas; in terms of control method, PID control in the negative feedback control method is adopted. 2. The time-segmented control technology of oxygen computer for electric arc furnace as claimed in claim 1, characterized in that the fuel supply rate in the oxygen-burning fluxing module is controlled by time intervals in the fluxing system as follows: F _oil ＝60·W _S ·V _oil /τ The oxygen supply rate in the fluxing system is: $f_o=\frac{60k_1\&CenterDot;W_S\&Center\; Dot;q\&Center\; Dot;V_{\mathrm{the\; oil}}\&Center\; Dot;V_o}{(1+\frac{0.2k_2\mathrm{\&alpha;}}{100-k_2\mathrm{\&alpha;}})\mathrm{\&tau;}}$ The supply rate of atomizing air in the fluxing system is: $f_A=\frac{60k_1\&Center\; Dot;W_S\&CenterDot;q\&Center\; Dot;V_{\mathrm{the\; oil}}\&CenterDot;V_o}{(\frac{100}{k_2\mathrm{\&alpha;}}-0.79)\mathrm{\&tau;}}$

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